The present invention relates to a semiconductor device, and, for example, to a semiconductor device for transmitting and receiving signals between circuits operating at different power supply voltages by using an isolator such as a transformer.
In recent years, many systems have been proposed for controlling a power device handling a high voltage by a control circuit operating at a lower voltage than the voltage supplied to the power device. In such a system, an isolator is used to transmit and receive signals between circuits operating at different voltage sources. An example of a semiconductor device that performs communication using such an isolator is disclosed in JP-A-2013-229815.
The semiconductor device disclosed in JP-A-2013-229815 includes: a transmission circuit that operates in a first power supply system and outputs a pulse signal based on an input data signal and a first retransmission request signal; a receiving circuit that operates in a second power supply system different from the first power supply system and restores a data signal based on a pulse signal; and an insulating coupling element that couples the transmission circuit and the receiving circuit with a magnetic field or an electric field, and the transmission circuit generates a delayed data signal and a first delayed retransmission request signal by delaying the data signal and the first retransmission request signal, respectively, outputs the pulse signal at the edge of the delayed data signal and the first delayed retransmission request signal, and prohibits the output of the pulse signal at the edge of the first delayed retransmission request signal for a predetermined period spanning the edge of the delayed data signal. In the technique described in Patent Document 1, the erroneous transmission of data is prevented by prohibiting the output of the pulse signal at the edge of the first delay retransmission request signal for a predetermined period of time spanning the edge of the delayed data signal.